Exposure to environmental conditions, such as temperature, moisture and pressure, can have a marked effect upon the storage or shelf life of many products. Many chemicals and biological products, for example those used in medicaments, are sensitive to changes in temperature and/or moisture, with relatively small variations in either leading to instability and breakdown due to chemical hydrolysis and/or microbial decay. Product stability may also be influenced by light and UV levels, necessitating the incorporation of various UV stabilisers in many chemical and biological formulations.
A wide range of other products are also sensitive to environmental change. Foodstuffs, such as fresh foods and drinks, are extremely susceptible to temperature fluctuations, both high and low temperatures causing deterioration in the quality of the food or drink due to chemical and/or microbiological degradation.
The manufacture and distribution of many products, particularly medicaments, requires careful monitoring of environmental exposure to ensure compliance with product specifications. Manufacturers are known to incorporate sensors of various types into their products in order that they can monitor environmental exposure and thereby the quality of their product. For example, temperature sensors are used in the food industry to indicate the temperature of food products and even record their previous exposure to a range of temperatures.
Similar devices are employed to indicate whether frozen foodstuffs have been allowed to thaw and refreeze.
These methods, however, are expensive as they require individual sensors to be attached to each product.
The Applicants have now devised an improved method of monitoring environmental exposure of a product, particularly from the point of manufacture to sales. Furthermore, the method can be used to check environmental compliance of the product throughout the manufacture-distribution-storage process. The method involves associating a passive radiofrequency identification (RFID) tag or transponder with an object, or a container for the object, and writing environmental data to the tag from a separate sensor exposed to the same environmental conditions. The environmental data are read, on energising by a reader/writer, either continuously or at defined points throughout the manufacture-distribution-storage process and checked for compliance against defined criteria. Non-compliance results in rejection of the object and/or recall of the object by the manufacturer. Alternatively, non-compliance may result in a reduction of the effective shelf-life of the object, as in the case of medicaments and perishable goods.
The RFID tag can be configured to have a memory structure which allows for large amounts of discrete information to be stored thereon. Transfer of information to or from the memory is readily achievable by the use of a reader/writer which is typically remote from the object, thereby minimising the need for direct product handling. In further aspects, the reader/writer can be arranged to simultaneously read, or write to, the memory of multiple RFID tags on multiple objects.
A principal advantage of the present invention is the capability of the memory of the RFID tag to store many environmental data items which are written to the memory at various defined points in the manufacturing-distribution-storage process. The memory thereby provides a detailed and readily accessible ‘environmental exposure’ history. The environmental information could, for example, also include date and time stamps. The memory might also be configured to include a unique serial number stored in encrypted form or in a password protectable part of the memory which uniquely identifies the product. The information could also include basic product information such as the nature of the product and usage information, customer information and distribution information such as the intended product destination.
The use of RFID tags to monitor environmental exposure is known in the art. Thus GB 2308947 discloses RFID tags having sensors incorporated within the transponder which can transmit environmental data to a remote reader on energising therefrom. Similar devices relating to RFID tags possessing built-in sensors are described for biomedical GB 2297225 and agricultural GB 2249001, GB 2076259 applications.
The principal advantages of the Applicant's invention over those disclosed in the literature are those of simplicity and cost. By eliminating the need to build individual sensors into each tag the Applicant's have devised a simplified method of monitoring environmental exposure at significantly reduced cost to the user.